The invention relates to an optical conductor comprising a rod-like part made of a light-conducting material.
Today, optical conductors mentioned above are well known, for instance, from various measurements, which measure properties of different substances, such as properties of solutions. An example of such devices is a refractometer. Another example is a calorimeter.
In association with measurements, reference measurements must often be carried out. A reference measurement is carried out by passing part of light to be passed to an object to be measured to a reference detector. The above-mentioned reference measurement is implemented, for instance, by using a semi-transparent mirror, by which part of light to be directed to the measurement object is led to the reference detector.
In principle, the arrangement based on a semi-transparent mirror operates well. The problem of the principle is, however, its complexity. Conditions in practical industrial processes are demanding, so the measuring devices have to be physically durable. Problems are caused, for instance, by vibrations and temperature changes. It is fairly difficult to accomplish a solution based on a semi-transparent mirror which is physically durable, since solutions based on a mirror and lenses are quite sensitive to vibrations, for example, as the positions of the mirrors and the lenses change easily due to the vibration. The problem is made worse by the fact that even small changes in the positions of the mirror or the lens may lead to large errors or cause total inoperativeness of the entire device. Because of the complexity the structures are also relatively expensive and the maintenance costs thereof are disadvantageously high. In some cases, a further problem is that the structures are relatively large.